High-Linearity Bandstop Filter with Frequency and Bandwidth Tunability Utilizing Phase-Change Material Switches

This paper demonstrates a frequency- and bandwidth-tunable absorptive bandstop filter. Low-loss, high-linearity phase-change material (PCM) switches are used for all reconfigurable elements. The filter's center frequency can be tuned from 420–730 MHz, and the bandwidth can be tuned from 0–165 MHz at the center of the filter's frequency tuning range. The filter has extremely high linearity, measured at >+40 dBm OIP3, limited only by the noise floor of the measurement setup. The die size is 5×5 mm2, and the total filter footprint including surface-mount capacitors and air-core inductors is 15 x 20 mm
²
.